金屬(Al)/ 鋁酸鑭（LaAlO3）/矽(Si)薄膜電容器與場效電晶體之製作與電性分析

Abstract

Lanthanum aluminate (LaAlO3) is considered as a potential candidate for high-K dielectric applications. LaAlO3 has high dielectric constant (13-27), large energy band gap (over 5eV), high thermal stability (up to 850°C), low leakage current density, large electron band offset. The structure of Al/LaAlO3/Si capacitors and transistors were fabricated successfully. The oxide films were deposited by rf-sputtering. The leakage current density was 4.36×10-3A/cm2 when the applied voltage was -1V. The measured dielectric constant was 13.4. The dominant electrical conduction mechanism of LaAlO3 thin film was Schottky emission mechanism at 450K. The electron barrier-height between Al/LaAlO3 interface and electron effective mass in the LaAlO3 film were about 0.94 eV and 0.07 m0, respectively. Secondary ion mass spectrometry (SIMS) and X-ray diffraction (XRD) were also used to examine the material properties of LaAlO3. The electrical characteristics of N-channel metal-oxide-semiconductor field effect transistors were also measured. The interface trapped charge density, effective electron mobility and sub-threshold swing were 2.27x1012cm-2-eV, 210cm2/V-s and 82.8 mV/dec., respectively. The degradation mechanisms of effective electron channel mobility and the threshold voltage shift in LaAlO3-gated n-MOSFETs were studied by analyzing experimental data at various temperatures from 11 K to 450 K. The mechanisms that influence the electron mobility include coulomb scattering, phonon scattering, surface roughness scattering.